import createApp from './main';

const isDev = process.env.NODE_ENV !== 'production';

// This exported function will be called by `bundleRenderer`.
// This is where we perform data-prefetching to determine the
// state of our application before actually rendering it.
// Since data fetching is async, this function is expected to
// return a Promise that resolves to the app instance.
export default context => new Promise((resolve, reject) => {
    const s = isDev && Date.now();
    const { app, router, store } = createApp();

    const { url } = context;
    const { fullPath } = router.resolve(url).route;

    if (fullPath !== url) {
        // console.log(fullPath)
        // console.log(url)
        return reject(new Error(fullPath));
    }

    // set router's location
    router.push(url);

    // wait until router has resolved possible async hooks
    router.onReady(() => {
        const matchedComponents = router.getMatchedComponents();
        // no matched routes
        if (!matchedComponents.length) {
            return reject(new Error(`entry-server 404 ${url}`));
        }
        // Call fetchData hooks on components matched by the route.
        // A preFetch hook dispatches a store action and returns a Promise,
        // which is resolved when the action is complete and store state has been
        // updated.
        Promise.all(matchedComponents.map(({ asyncData }) => asyncData && asyncData({
            store,
            route: router.currentRoute,
        }))).then(() => {
            isDev && console.log(`data pre-fetch: ${Date.now() - s}ms`);
            // After all preFetch hooks are resolved, our store is now
            // filled with the state needed to render the app.
            // Expose the state on the render context, and let the request handler
            // inline the state in the HTML response. This allows the client-side
            // store to pick-up the server-side state without having to duplicate
            // the initial data fetching on the client.
            context.state = store.state;
            resolve(app);
        }).catch(reject);
    }, reject);
});
